System for machining work pieces comprising at least one machine tool

ABSTRACT

An installation for machining work pieces ( 15 ) comprises at least a machine tool ( 36 ). It is provided with a supply and take-down equipment ( 41 ), which is disposed before the machine tool ( 36 ) on a side of the working area ( 14 ) that faces away from the work spindle ( 10 ).

[0001] The invention relates to an installation according to thepreamble of claim 1.

[0002] In machine tools of the generic type known from EP 0 742 072 B1(corresponding to U.S. Pat. No. 5,662,568 A) and EP 0 996 446 A1(corresponding to U.S. Ser. No. 09/161,891), the supply of work piecesfor machining takes place in a way not described in detail. Customarily,the supply takes place laterally or from above into the working area.

[0003] DE 43 24 575 A1 (corresponding to U.S. Pat. No. 5,321,874)teaches to link successive machine tools to one another in such a waythat a conveyor path is disposed above the machine tools and above thework holding fixtures that are in front thereof; horizontal carriagesare displaceable on the conveyor path, having vertically movable holderbeams, each bottom end of which being provided with work piece-transfermeans in the form of grippers, which place the work pieces from above onthe stationary work holding fixtures that belong to the machine tool,and lift them off upwards after working. The space requirements of sucha design are extraordinary.

[0004] AT-PS 288 112 teaches an installation for machining work piecesthat comprises several successive machine tools. A carriage is disposedfor displacement on rails that are disposed on the floor in front of themachine tools. The carriage has forks in the way of a fork lift, bymeans of which to convey palletized work pieces from a supply rack tothe respective machine tool. The pallets are inserted laterally into theworking area of the machine tool, after which they are depositedvertically. This design too is rather complicated constructionally; itrequires a lot of space and is accompanied with rather time-consumingsupply and take-down jobs.

[0005] DE 195 16 849 C2 (corresponding to U.S. Pat. No. 6,135,696)teaches to interlink side-by-side machine tools so that work pieces aresupplied from below to the machine tools. This offers the possibility ofcompact structure with reduced moving masses and short supply andtake-down times, however, chips and cooling lubricants will drop fromthe machining place towards the supply and take-down equipment, theprotection of which from cooling lubricants and chips not being possibleor implying vast constructional requirements. Complicated motions of thework piece grippers of the supply and take-down equipment are necessaryto reach the work holding fixtures of the machine tool.

[0006] It is an object of the invention to embody an installation of thegeneric type such that supply and take-down jobs are possible withoutcostly constructional implementation and at reduced supply and take-downtimes, accompanied with high operational safety.

[0007] This object is attained by the features in the characterizingpart of claim 1. The measures according to the invention render theinstallation according to the invention very compact, meaning areduction in moving masses and in the supply and take-down motions ofthe work piece transfer means. This arrangement ensures that only veryfew cooling lubricants and chips will move from the working area to thesupply and take-down equipment. Transfer from the supply and take-downequipment to the work holding means of the machine tool and vice versatakes place exclusively by horizontal motions of the work holding meansand/or of the work transfer means both being preferably equiaxedaccording to claim 2.

[0008] The embodiment according to claims 3 and 4 leads to furthersimplification of the supply and take-down equipment.

[0009] The improvement according to claims 5 and 6 specifies highlysimple designs of the z-displacement means.

[0010] Preferably, the measures of the invention are used forinterlinking several machine tools in accordance with claim 7 or 8.

[0011] In keeping with the further embodiment according to claim 9, afirst work piece transfer means serves for holding a work that has beenmachined by the machine tool, while another work piece transfer meansserves for feeding a work that is to be machined, which further reducessupply and takedown times.

[0012] The embodiment of claim 10 may be favorable in particular forbasic adaptation to differing work pieces.

[0013] The improvement according to claim 11 enables a work to be seizedand released rapidly, promoting the reduction of supply and take-downtimes.

[0014] In keeping with the embodiment according to claim 12, a workpiece can be chucked in successive machine tools in positions that aretwisted one relative to the other. Furthermore, a work piece can berotated, for instance after machining, so that chips and/or coolant areremoved.

[0015] The further embodiments according to claims 13 and 14, on theside of the machine tool, serve for rapid conveyance of the work piecefrom the place of transfer to the place of machining and possibly forhandling at the place of machining.

[0016] Further features, advantages and details of the invention willbecome apparent from the ensuing description of an exemplary embodiment,taken in conjunction with the drawing, in which

[0017]FIG. 1 is a side view of a machine tool with a supply andtake-down equipment;

[0018]FIG. 2 is an elevation, on the line II-II of FIG. 1, of themachine tool according to FIG. 1;

[0019]FIG. 3 is a plan view of the supply and take-down equipment inaccordance with the arrow III of FIG. 1;

[0020]FIG. 4 is a perspective plan view of a diagrammatic illustrationof an installation comprising several machine tools and a supply andtakedown equipment;

[0021] FIGS. 5 to 7 are strongly diagrammatic side views of a machinetool comprising a supply and take-down equipment, with the work piecetransfer means and the work piece-holding means in varying positions;

[0022]FIG. 8 is a lateral view of a part of the machine tool, comprisinga modified embodiment of a supply and take-down equipment;

[0023]FIG. 9 is a plan view of the supply and take-down equipment inaccordance with the arrow IX of FIG. 8;

[0024] FIGS. 10 to 12 are partial plan views of the supply and take-downequipment in varying positions of the work piece grippers thereof;

[0025]FIG. 13 is a plan view of another embodiment of a supply andtake-down equipment; and

[0026]FIG. 14 is a perspective plan view of a diagrammatic illustrationof an installation with several machine tools and a supply and take-downequipment.

[0027] As seen in particular in FIGS. 1 and 2, a frame 2 is mounted on amachine bed 1. Mounted on a front 3 of the frame 2 is an x skid 4 forhorizontal displacement in an x direction on x guides 5. Actuation takesplace by means of x linear motors 6. Mounted on the x skid 4 is a y skid7 for vertical displacement in the y direction on y guides 8. Actuationtakes place by means of y linear motors 9. Disposed on the y skid 7 is awork spindle 10, which is rotatably drivable by a motor (not shown) andhas a tool holding fixture 11 on its end that faces away from the frame2. The work spindle 10 extends in the direction towards the frame 2through an opening 12 in the x skid 4 between the y guides 8 and reachesinto the frame 2. The work spindle 10 extends in a z directionperpendicular to a vertical plane spanned by the x direction and the ydirection. The work spindle motion unit 13 in the form of a cross-skid,which has been described so far, has a basic structure that is generallyknown as a box-in-a-box mode of construction and has been illustratedfor instance in EP 0 742 072 B1 (corresponding to U.S. Pat. No.5,662,568 A). By alternative displaceability of the work spindle on thex-y plane may also be effected by couplers as known from EP 0 916 446 A1(corresponding to U.S. Ser. No. 09/161,891).

[0028] Located in front of the tool holding fixture 11 and the workspindle 10 is a working area 14, where a work piece 15 is machined by atool 16 that is held in the tool holding fixture 11. Arranged above thisworking area 14 is a top frame 17, which is composed of longitudinalbeams 18 that run in the z direction and crossbeams 19, 20 that run inthe x direction, and which, at its end turned away from the frame 2,supports itself via props 21 on the machine bed 1. Big advantages areoffered by this rather rigid overall construction of a machine frame 22which comprises the machine bed 1, the frame 2, the top frame 17 and theprops 21. This machine frame 22 defines the working area 14.

[0029] A z skid 23, which is movable in the z direction, is led on zguides 24 by means of guide shoes 24 a for displacement between thelongitudinal beams 18 of the top frame 17. Actuation takes place by zlinear motors 25. By alternative, actuation in the x, y and z directionmay also be effected by rotary motors, for instance electric motors, viaball bearing spindles.

[0030] Attached to the underside of the z skid 23 is a work pieceturntable 26 which is mounted for rotary actuation about its vertical,y-directed center line 27 by a turntable drive motor 28. Attached to theunderside of the turntable 26 are work piece holding means in the form awork holding fixture 29 with a recess 30 that is suited to a fittingpiece 31 substantially in the form of a plate that bears the work piece15. The holding fixture 29 further comprises holding-fixture chuckingdevices 32 which are actuated by chucking actuators 33. By means of jaws34, the chucking devices 32 retain the fitting piece 31 in the recess 30of the holding fixture 29, whereby the work piece 15, which is mountedin a precisely defined position on the fitting piece 31, obtains aprecisely defined position relative to the holding fixture 29 and thusto the turntable 26.

[0031] The chucking devices 32 are located above and underneath therecess 30, holding the fitting piece 31 in its top and bottom area. Asseen in particular in FIG. 1, the work piece 15, in each position of thez skid 23 and in each position of rotation of the turntable 26, projectsover the entire working area 14 into a position free from the workholding fixture 29. Located underneath the work piece 15 is a chipremoval arrangement 35 in the form of chip clearances.

[0032] Of the machine tools 36 specified so far, several machine tools36 a to 36 f (see FIG. 4) of fundamentally identical design are providedside by side in a row in the x direction, serving for various jobs ofmachining one and the same work piece 15; they are interlinked,constituting a flexible manufacturing system. FIG. 3 illustrates onlytwo machine tools 36 a, 36 b of them.

[0033] On the supply and take-down side 37, which is allocated to theprops 21 and, therefore, located on the side of the machine tools 36 ato 36 f opposite the work spindle motion unit 13, provision is made fora conveyor path 38 which interconnects the machines 36 a to 36 f and isfixed to the machine frames 22, in particular to the respective machinebed 1. The conveyor path 38 comprises a top and a bottom Vee guide 39,40, on which a supply and take-down equipment 41 is guided fordisplacement in the x direction. It has a horizontal carriage 42 as an xskid which is led on guides 39, 40 for displacement free from floatingand tilting by means of rolls 43 that are spaced apart in the xdirection. Actuation takes place by an x electric motor 44 in the formof a gear motor by way of a gear 44 a and a pinion 44 b or,alternatively, by way of a synchronous belt drive. By alternative,actuation may also take place by a linear motor, in particular by along-stator linear

[0034] drive. The carriage 42 has a vertical beam 45, which extends inthe y direction and on which a y skid 47 is disposed for verticaldisplacement in the y direction by means of y guides 46. Actuation takesplace by means of a y electric motor 49. The y carriage 47, whichextends substantially horizontally in the z direction, has two z rails50, on each of which is guided a z skid 52 and 53 for displacement inthe z direction as z-displacement means; the z skid 52 and 53 isdrivable by a z electric motor 51.

[0035] The z skids 52, 53, which stand out from the y skid 47 in the xdirection, are provided with work piece grippers 54 and 55 as work piecetransfer means; the grippers 54 and 55 are oriented in the z directiontowards the working area 14 and equipped with gripping jaws 56, each ofwhich being opened and closed by a gripping-jaw drive 57 and 58. Thework piece grippers 54, 55 are jointly displaceable in the y directionand independently displaceable in the z direction; they can be openedand closed independently of each other. In the x direction, they take agiven fixed position relative to one another on the beam 45 of thecarriage 42. Furthermore, a rotary actuator 54 a and 55 a is provided ineach case, by means of which the respective gripper 54 and 55 ispivotable about its center line 54 b and 55 b which runs in the zdirection.

[0036] The mode of operation is explained in conjunction with FIGS. 1 to3 and FIGS. 4 to 7, which are strongly simplified as compared to thedesign according to FIGS. 1 to 3. This is why structural componentswhich are strongly simplified as compared to FIGS. 1 to 3 have the samereference numerals as in FIGS. 1 to 3, however provided with a prime.

[0037] As seen from the above-mentioned FIG. 4, a greater number ofmachine tools 36 a to 36 f are linked together by the conveyor path 38,along which the supply and take-down equipment 41′ is movable in the xdirection. Upstream of the conveyor path 38 is a feed and dischargeequipment 59, for instance in the form of a conveyor belt, on which workpieces 15 that are to be machined are supplied, for example sitting onthe fitting pieces 31, and on which finished work pieces 15 aredischarged together with their fitting pieces 31. For placement of thework pieces 15 from the feed and discharge equipment 59 on to the supplyand take-down equipment 41, and from there again on to the feed anddischarge equipment 59, provision is made for a transfer equipment 60 ata place where the conveyor path 38 and the feed and discharge equipment59 meet.

[0038] If a machined work piece 15 is in the work holding fixture29′—which will presumably be so during a conventional manufacturingprocess—then the work piece turntable 26 and the work holding fixture29′ are in the transfer position seen in FIGS. 1, 5 and 6, which is invicinity to the supply and takedown equipment 41′. In this position, theturntable 26 is pivoted such that the work piece 15 (not shown in thisposition in FIGS. 5 and 6) is turned towards the equipment 41′. Bycorresponding displacement in the y and z direction, the gripper 54′,which holds no work piece 15, can seize the work piece 15 by thegripping jaws 56 being closed and remove it from the holding fixture 29′after release of the chucking jaws 34. The gripper 54′ is then run inthe z direction out of the machine tool 36 c. Afterwards the horizontalcarriage 42 is moved in the x direction and the work piece gripper 55′in the y direction sufficiently far for the work piece 15, which isseized thereby and still remains to be machined, to move before the workholding fixture 29′, which is still in the transfer position, as seen inFIG. 5.

[0039] Then the z skid 53′, which holds the work piece 15 that is to bemachined, and the gripper 55′ are moved from the x conveying positionseen in FIG. 5 towards the work holding fixture 29′, corresponding toFIG. 6, to such an extent that the holding fixture 29′ can take up thework piece 15 as illustrated in FIGS. 1 to 3 and as specified above.When the chucking devices 32 have been closed, the gripping jaws 56 openso that the work piece 15 is exclusively held in the work piece holdingfixture 29′. The z skid 23 is then moved in the z direction towards thetool 16, the work piece 15 being simultaneously pivoted about the axis27. In the position seen in FIG. 7, it is machined. The motions of thetool 16 and the work piece 15 relative to one another are performed bythe x skid 4, the y skid 7, the z skid 23 and the turntable 26.

[0040] Return transfer of the machined work piece 15 then takes place inthe way described, by displacement of the z skid 23 and by rotation ofthe work piece turntable 26 into the position of transfer.

[0041] Machining takes place in each machine tool 36 a to 36 f. For allmachines to be able to operate simultaneously, one or several supply andtake-down equipments are provided on the conveyor path 38.

[0042] FIGS. 8 to 12 illustrate a modified embodiment of a supply andtake-down equipment 61. In as much as parts are available, which areidentical or nearly identical with those of FIGS. 1 to 4, they have thesame reference numerals, there being no need of renewed description.

[0043] The y skid 47 of the supply and take-down equipment 61 isvertically drivable by the y electric motor 49 by way of a ball-bearingspindle drive 62. For displacement of the work piece grippers 54 and 55that serve as work piece transfer means, it comprises parallel bars asz-displacement means 63, 64. They have a main pivoted lever 65 which islodged in a pivot bearing 67 on a gear box 66 that is fixed to the yskid 47, pivoting about a vertical pivot axis 68 that runs in the ydirection. Pivoting takes place by means of an electric z pivot-drivemotor 69 which is flanged to the gear box 66. By its end opposite thepivot bearing 67, each main pivoted lever 65 is connected with a holder70 which holds the respective work piece grippers 54 and 55. In parallelto the main pivoted lever 65, provision is made for a parallel-motionlever 71, which is articulated to a bracket 66 a that is mounted on thebox 66 and to the holder 70 so that the respective holder 70, togetherwith the gripper 54 and 55, is moved in parallel to itself upon swingsof the main pivoted lever 65. A rotary drive 54 a and 55 a is mounted onthe holder 70, by means of which to pivot the respective gripper 54 and55 about its center line 54 b and 55 b that runs in the z direction.

[0044] The partial illustrations in FIGS. 10 to 12 show that wheneverthe work piece grippers 54 or 55 are to be shifted not only parallel tothemselves, but straightly in the z direction, the horizontal carriage42 must be moved in the x direction, depending on the position ofpivoting of the pivoted lever 65 together with the parallel-motion lever71. The mentioned straight displacement of the grippers 54, 55 isproduced by a superposed motion of the z-displacement means 63 and ofthe horizontal carriages 42. For clarification purposes, the work piecegrippers 55 are shown one precisely on top of the other in FIGS. 10, 11and 12 so that it is recognizable in which way the horizontal carriage42 must be moved in the x direction for straight motion of the grippers55 to be obtained. Otherwise, the procedure is as described above.

[0045] In the embodiment according to FIGS. 13 and 14, components thatare identical with or very similar to parts already described have thesame reference numerals, there being no need of renewed description. Theillustrated supply and take-down equipment 72 comprises z displacementmeans 73 and 74, which have a main pivoted lever 65 in the place of theparallel bars of FIG. 9. This main pivoted lever 65 is pivotably mountedon the y skid 47; it can be pivoted by the respective z pivot drive 69.The holder 70, which bears the respective work piece gripper 54 and 55,is connected to the main pivoted lever 65 by way of a guide drivingmotor 75, by means of which any motion of the gripper 54 and 55 about apivot axis 76 in the y direction is possible.

[0046] As seen in FIG. 13 in combination with FIG. 14, this supply andtake-down equipment 72 may also serve for operation of two rows ofmachine tools 36 a to 36 f that are opposite to one another. In thiscase, a gripper 55 can be used for operation of the row of machine tools36 a to 36 c—at the top of FIG. 14—whereas the other gripper 54 servesfor operation of the row of machine tools 36 d to 36 f—at the bottom ofFIG. 14. Each of the grippers 54, 55 may just as well be used for onlyone respective row, there being nearly unlimited flexibility.

1. An installation for machining work pieces (15), comprising at leastone machine tool (36), which has a machine bed (1), a frame (2) joinedto the machine bed (1), a work spindle (10), which, by means of a workspindle motion unit (13) that is disposed on the frame (2), is movableon a plane spanned by a vertical x direction and a horizontal ydirection, and which is designed for holding a tool (16), and whichextends vertically to the plane in a z direction, a working area (14)disposed on the machine bed (1) before the work spindle (10) in the zdirection, and work piece holding means (29), which include chuckingdevices (32) for a work piece (15) and which are disposed in the workingarea (14); and at least one supply and take-down equipment (41, 61, 72);characterized in that the supply and take-down equipment (41, 61, 72) isdisposed before the machine tool (36) and—in the z direction—before theside of the working area (14) that faces away from the work spindle(10); in that disposed before the machine tool (36) is a conveyor path(38), which runs substantially in the x direction and on which thesupply and take-down equipment (41) is displaceably supported; in thatthe supply and take-down equipment (41, 61, 72) has at least a workpiece transfer means (54, 55); and in that the work piece transfer means(54, 55) and/or the work piece holding means (29) is displaceable in thez direction for transfer of a work piece (15) from the work piecetransfer means (54, 55) to the work piece holding means (29) and viceversa.
 2. An installation according to claim 1, characterized in thatthe work piece holding means (29) as well as the work piece transfermeans (54, 55) are displaceable in the z direction.
 3. An installationaccording to claim 1, characterized in that the supply and take-downequipment (41, 61, 72) comprises an x skid (38), which is movable on theconveyor path (38) and is provided with at least a z-displacement means(52, 53; 63, 64; 73, 74) which is movable in the z direction and onwhich is mounted the work piece transfer means (54, 55).
 4. Aninstallation according to claim 1, characterized in that the work piecetransfer means is a work piece gripper (54, 55).
 5. An installationaccording to claim 1, characterized in that the work piece transfermeans (54, 55) is displaceable straightly in the z direction by a z skid(52, 53).
 6. An installation according to claim 1, characterized in thatthe work piece transfer means (54, 55) is displaceable in the zdirection by a pivoted lever (65) which is drivable for pivoting.
 7. Aninstallation according to claim 1, characterized in that several machinetools (36 a to 36 f) are arranged side by side in a row; and in that theconveyor path (38) runs in front of the machine tools (36 a to 36 f). 8.An installation according to claim 1, characterized in that severalmachine tools (36 a to 36 f) are arranged in two opposite rows; and inthat the conveyor path (38) runs between the two rows of machine tools(36 a to 36 f).
 9. An installation according to claim 1, characterizedin that the supply and take-down equipment (41, 61, 72) comprises twowork piece transfer means (54, 55), which are disposed side by side inthe x direction and actuated independently of one another.
 10. Aninstallation according to claim 1, characterized in that the at leastone work piece transfer means (54, 55) is displaceable in the ydirection.
 11. An installation according to claim 1, characterized inthat the work piece transfer means (54, 55) comprises a gripper drive(57, 58).
 12. An installation according to claim 1, characterized inthat the work piece transfer means (54, 55) is pivotable about a centerline (54 b, 55 b) that runs in the z direction.
 13. An installationaccording to claim 1, characterized in that the work piece holding means(29) is suspended on a z skid (23) that is disposed in the y directionabove the work piece holding means (29).
 14. An installation accordingto claim 1, characterized in that the work piece holding means (29) issuspended on a work piece turntable (26), which is disposed in the ydirection above the work piece holding means (29) and rotary about anaxis (27) that runs in the y direction.